Character in a series of children's books by Mercer Mayer. (Possibly in the same universe as Mayer's other book Professor Wormbog in Search of the Zipperump-A-Zoo, as both Little Monster and Professor Wormbog seem to have a pet Kerploppus.) Little Monster appears in all sorts of books, including most recently elementary-level books and playsets featuring him as a private eye. There are also some CD-Is for preschool children featuring him.